The use of endoscopes has successfully proven itself in surgery for many years, and serves in many cases as a minimally invasive alternative procedure to the conventional open surgery. To be able to examine the area of application and to operate there by means of the endoscope optic, which can take the classic form for instance of a relay lens system, a fiber image conductor, or else as an electronic image sensor chip (CMOS, CCD) for video image photography, it is absolutely essential to illuminate the area of examination as well as possible. Besides their use in human and veterinary medicine, endoscopic examinations have also proven effective in technical areas, for instance for examining hollow cavities. Even in these application areas, good illumination of the area of examination is indispensable for good imaging by the endoscope optic.
The illumination of an area of investigation is normally provided by a light conductor, consisting of fiberglass clusters, by which light from an external light source is conducted into the area of examination. Because this lighting system, for instance for purposes of cooling and wiring, is technically very complex, it has been a familiar practice in the art for some time to use lighting systems that are provided with LED elements and are affixed on the distal end of the endoscope shaft. The advantage of these LED lighting systems mounted on the distal end is that they avoid coupling losses in the light conductors and the LED elements have a long useful life.
The use of a lighting unit that includes a lighting system for endoscopic examinations with an LED element is, for instance, known from DE 100 61 107 A1. The disadvantage of the known lighting systems, however, is the low effective density that is to be produced associated with the LED elements, so that even with special arrangements of the LED elements on the distal front end of the endoscope shaft, it is only possible to produce an illumination of the area of examination that is not sufficient for all cases of application.
Consequently it is the object of the invention to create a lighting system for endoscopic examinations of the aforementioned type, which ensures a constantly sufficient illumination of the area of examination.